Camera functional accessories are commonly used in enhancing function of a camera and expanding its application scope. Common functional accessories such as flashlight, adaptor and remote control are attached to a camera via hot shoe. Hot shoe is a fixed slot on various digital imaging apparatus for attaching various external accessories. Generally, there is, on a camera, a hot shoe in the shape of a dovetail slot. At the lower end of a camera adaptor, there is a hot shoe connector inserted into the dovetail slot-shape hot shoe. Contacts on the hot shoe may match with electrical contacts on the hot shoe connector. Since hot shoe varies on cameras of different types, an accessory cannot be universally applied to different cameras. For example, a Nikon camera can only use a flashlight which may match with Nikon cameras, and a Canon camera can only use a flashlight which can match with Canon cameras. The fact that such accessory cannot be applied to different cameras increases the cost for users to buy.
For the above problem, there is provided in prior art some all-purpose accessories such as flashlight and remote control which may be compatible with various cameras. Since hot shoes of most cameras contain a shared contact, flashlights and remote controls of different types may be connected via the shared contact to perform flashing or remote controlling. However, as other contacts are not connected, other Through-the-Lens (TTL) parameters cannot be transmitted, and thus TTL or further functions of flashlight cannot be performed.
Referring to FIG. 4 which is a design in a second prior art, electrical contact set 43 of a functional accessory such as flashlight, adaptor and remote control is optimized to be adaptive to both Canon and Nikon hot shoes, with which one accessory may be applied to two types of cameras. Besides, TTL function is also realized as multiple contacts are connected. The electrical contact set 43 of this type of flashlight uses 8 contacts, including a shared trigger 431, a first clock foot 432, a second clock foot 433, a camera data input foot 434, a flashlight signal detection foot 435, an input and output data foot 436, a flashlight data output foot 437 and a chip select signal foot 438; wherein, the 6 symmetric contacts are the first clock foot 432, the second clock foot 433, the camera data input foot 434, the flashlight signal detection foot 435, the input and output data foot 436, and the flashlight data output foot 437. The above 6 electrical contacts are very close to each other, and they may be easily worn out after frequent plug-in and plug-out, which may finally cause short circuit and destroy the device.
In prior art, other technical solutions are also tested. For example, patent publication CN201466439U discloses a multipurpose flashlight hot shoe socket. With the 8 contacts having a certain arrangement, the socket may always have contact that may connect cameras of different brands, and thus electrical connection with multiple systems of cameras of different brands is realized. Such technical solution also has the defects as described above, that is, electrical contacts in the electrical contact set are arranged very close to each other so as to simply realize electrical connection with different cameras. In this case, electrical contacts will be seriously worn out after frequent plug-in and plug-out, shot circuit may easily occur and the device may be damaged.
Therefore, short circuit caused by wear to electrical contacts of functional accessories is an issue that should be solved by technical person in the art urgently.